This iterator will insert values into a property of each of the records returned.
The values to be inserted come out of another traversal object. This is useful
when you have two separate collections and want to merge them together by placing
each of the values from one collection into a property inside the other collection.

Implements a simplistic version of the popular Map-Reduce algorithm. Acts
like an iterator for the original passed data after each result has been
processed, thus offering a transparent wrapper for results coming from any
source.